#include
#include
#include
#include
void main()
{
int num=0,add=0; /* 答题数,得分 */
int score[3]={10,7,5};
char str[20],str1[10][20];
while(1)
{
int a=0,b=0,d=0,c=0,k=0,i=0,j=-1,result;
char sf[2]={'+','-'};
/* 出题 */
while(1)
{
a=rand()%51;
b=rand()%51;
d=rand()%2;
if(d==0)c=a+b;
else c=a-b;
if(c>=0 && c